Telephone system



C. L. GOODRUM.

TELEPHONE SYSTEM.

APPLICATION FILED JULY 26,1917.

Patented; Apr. 20, 1921]) W 0 0 /0 W6 W4 5 we H m Q W mmxw 5 mw .QN QX A WNW QW UNITED. STATES PATENT OFFICE.

CHARLES I. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent. Patented Apr. 20, 1920.

Application fi1ed July 26, 1917. Serial No. 182,977.

To all whom it may concern:

Be it known that I, CHARLES L. GooDRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems, wherein electro-mechanical switching apparatus is employed for extending a call from one subscribers station to another.

More particularly it is concerned with certain arrangements and adaptations of such apparatus that tend to secure a more eflicient and satisfactory telephone service for the subscribers.

In the operation of telephone systems it very frequently occurs that a called subscriber fails to respond on account of his absence at the timethe call is initiated. Upon returning he has no means of knowing that he has been called, and even in cases where the call is answered by an assistant or some other person, receiving instructions to deliver the message, it often happens that, through negligence, such message never reaches the desired party. The obvious result of such conditions is, that important calls failing to reach their destination may often work to the serious inconvenience and detriment of all concerned.

To avoid these undesirable conditions the present invention has for its object the provision of means whereby the calling subscriber may, upon discovering that the called subscriber is absent, operate his substation apparatus to produce a record at the called partys station, such as will 1nform the latter that he was called during his absence. This record also enables him to tell the number of the party that called, and if necessary may be adapted to give him such other arbitrary information as the circumstances require. To the attainment of the above object a recording device is installed at each substation. A calling subscriber may then operate his sender, after having completed the initiation of the call and failed to receive a response, to send a series of impulses over the line. With the connector switch in its ringing position at this time said seriesof impulses operate to disconnect the source of ringing current and to substitute therefor a special source of current, which in turnoperates the recording device at the called station to print or otherwise produce a record in accordance with the impulses transmitted.

A more thorough understanding of my invention may be had from a consideration of the following specification wherein its advantageous features are pointed out and described in detail. In the figure of the drawing accompanying said specification there is illustrated a portion of a telephone system comprising two substations and the necessary apparatus for extending a call from one to the other. Certain elements are conventionally shown for the sake of clearness.

Referring to the drawing, a description will be given of the process of extending a call from the substation 1 to the substation 2. Upon the subscriber at station 1 removing his receiver from the hook, a circuit is closed in the well known manner to start a line finder in operation to connect with the terminals of the calling line, and

thereby to extend said line over a trunk to an idle selector. Only the brushes 3, 1 and contacts 5, 6 of the finder switch are shown. The line is now in condition to receive the first set of impulses, corresponding in number to the first digit of the number of the substation 2. This series of impulses is sent by the subscriber at station 1 manipulating the dial 7, and serves to position the selector brushes 8, 9 and 10 in operative relation to a group of trunks leadin to a connector having access to the desire line. In a well known manner the brushes 8, 9 and 10 are thereupon moved automatically in a hunting movement over such group to seize the first idle trunk, which may be assumed to be the one having the-terminals 11, 12 and 13. The line thus being extended to the connector switch, generally designated at 14, a circuit is closed for the line relay 15 traceable from 15 attracts its armature to complete a cir-' cuit for the slow releasing relay 18. Sucli; circuit extends from free pole of battery; winding of relay 18, front contact and ar mature of relay 15 to ground. The relay 18 on" attracting its armature closes a break point in a circuit for a second slow releasing relay 19 and also for the primary stepping magnet PM. a

In the meanwhile the calling subscriber has rotated the dial of his sending device 7 preparatory to sending the tens digitimpulses. At the first impulse of the tens series, the resultant opening of the previously traced circuit of line relay 15 causes the armature to retract and close its back contact. A circuit is thereupon established for relay 19 leading from the free pole of battery, winding of such relay, conductor 20, side-switch arm 21 in its first position, front contact and right-hand armature of relay 18, back contact and armature of relay 15 to ground. Upon energizing, the relay 19 retract its armatures.

closes a circuit for the escape magnet 22, traceable from free pole of battery, contact and right-hand armature of relay 19, winding of escape magnet 22,- armature andnormally closed contact of ringing cut off relay 23 to ground. The escape magnet 22 which is designed to release the side switch from 'firstto second positions on deenergizing, by

thus attracting its armature places said side switch in readiness to be moved into its second position as soon as the proper conditions have been brought about. At the same time the relay 15 on retracting its armature closes a circuit for the primary ma net PM as v follows battery, winding of P v side-switch arm 24 in its first .position, conductor 20,

side-switch arm'21 in its first position, front cuit of relay 15 is maintained closed for aconsiderable period and thereby the armature ofsaidrelay is retained in its attracted position This causes a break in the circuit of slow releasing relay 19 for a sufiicient interval to permit the same to denergize and At its right-hand armature the relay 19 opens the circuit of escape magnet 22, which on deenergizing steps the side switch into second position.

a The switch is now ready to receive the last or units series of impulses, which impulses on being transmitted serve to vibrate the armatureof relay 15 as already described.

At its armature and back contact the relay 15 tot-ground. Relay 19 by attracting its I.rigl: 1 t. hand armature, establishes a circuit for escape magnet 22 as previously traced. Said escape magnet is also arranged to step theside switch from second to third positions upon denergizing. At each retraction of the relay 15, the secondary magnet SM receives an actuating impulse over the following circuit: battery, winding'of SM, sideswitch arm 24 in its second-position, conductor 20, side-switch arm 21 in its second position, front contact and right-hand armature of relay 18, back contact and armature of relay 15 to ground. In this manner the magnet SM steps the connector brushes 25, 26 and 27 over the selected group and brings them to rest on the contacts 28, 29 and 30 of the line leading to the desired substation. At the time the connector places its brushes upon the terminals of the called line the same may be idle, or it may be busy either by reason of the party thereat having previously initiated a call himself or by having been called by another subscriber. Assuming the substation 2 to be busy, there will be a guarding ground potential upon the test terminal 30 of the connector switch 14. If busy as a calling line, a ground is placed 011 the terminal 30 by a finder switch allotted to this line and which corresponds exactly to the finder whose brushes are shown at 3 and 4. If, on the other hand, said line is engaged as a called line a ground is put upon terminal 30 as follows: ground, side-switch arm, corresponding to arm 31, of the connector that has already appropriated the use of the line, third or fourth contact of said switch arm, to the mutiple test terminals of all connector switches having access to said line. side-switch arm 31 of a connector steps onto its third contact, which, as will hereinafter be seen, is the ringing position, a circuit is established for the cutoff relay 32. Relay 32, by energizing, opens the circuit of line relay 33. Relays 32 and 33 are individual to the line of substation 2, and when thus operated prevent the subscriber at this station from initiating a call.

With the brushes 25, 26 and 27 in contact with the terminals 28, 29 and 30 of connector 14, and with substation 2 busy, a ground will be discovered upon the terminal 30 by test wiper 27 as above noted. At the termination of the last series of impulses the relay 15 again holds its armature up sufficiently long to permit relay 19 to de'elnergize and release its armatures. At the left-hand armature and contact of relay 19 a circuit is now closed for release magnet RM. This circuit extends from free ole of battery, right-hand winding of R righthand armature and contact of relay 34, off-normal contact 35, which is closed at this time, con- Under this latter condition when the ductor 36, left-hand armature and contact of relay 19, conductor 37, side-switch arm 31 in, its second position, test wiper 27, to the grounded terminal 30. The release magnet energizes in this circuit and restores the connector switch to normal position and also completes an energizing circuit for the left winding of relay 34. At the time the relay l9 de'e'nergized, it opened the escape magnet circuit at its right-hand armature. However, as the escape magnet is slow to release and is controlled by the relay 19, there will be an interval of time between the release of relay 19 and the deenergizing of the escape magnet to move the side switch into position three. During this interval the relay 19 is again energized over the following circuit: free pole of battery, winding of relay 19, front contact and left-hand armature of relay 34, front contact and left-hand armature of relay 18, front contact and lefthand armature of release magnet RM lefthand winding of release magnet RM to ground. Relay 19 again energizing restores the circuit of escape magnet 22 and thereby prevents the release of the side switch into position three. The second energization of relay 19 just described 0 )ened the first circuit for release magnet R M, but this magnet is held energized over the circuit for relay 19 just traced. At its right-hand armature and contact, magnet RM completes a circuit for the busy back machine 38, whereby a characteristic sound is produced in the receiver at station 1, informing the party thereat that the called line is busy. The path for the busy tone machine may be traced as follows: ground, secondary winding of said machine, contact and right-hand armature of RM, conductor 39, condenser 40, conductor 17, contact 12, brush 9, brush 4, contact 6 through the telephonic apparatus including the receiver of substation 1, contact 5, brush 3, brush 8, contact 11, conductor 16, winding of relay 15 to ground. The calling subscriber thus being informed that the called line is busy replaces his receiver on the hook, thereby severing the energizing circuit of relay 15 which immediately retracts its armature. This deenergizes the slow release relay 18 which, after an interval, releases its armatures. A ground is now placed on the test terminal 13, as follows, to permit the release of the selector and finder switches: ground, armature and back contact of relay 15, righthand armature and back contact of relay 18, conductor 41, contact and left-hand armature of relay 34, test wire 42, to the test terminal 13.

If, however, the called line is idle, the relay 19 deenergizes at the cessation of the units series of impulses as before, but in this instance there is no ground on termnial 30 and hence the release magnet remains inactive. 'hen a sufiicient interval has elapsed after the disruption of the escape magnet circuit said magnet steps the side switch into third or ringing position. lVith the side switch in third position a circuit is completed as follows for the relay 19: free pole of battery, relay 19, conductor 20, sideswitch arm 24 in its third position, conductors 43 and 44, front contact and armature of relay 15 to ground. Relay 19 energizes in this new circuit and establishes the hereinbefore traced circuit for the escape magnet 22. At its armature and contact the escape magnet closes a circuit whereby signaling current is placed upon the called partys line. Said circuit extends from ground, through the ringing machine 45, armature and contact of magnet 22, relay, 23, back contact and armature of relay 46, conductor 47, side-switch arm 49 in its third position, wiper 26, terminal 29, conductor 51, through the ringer at station 2, conductor 50, terminal 28, wiper 25, side-switch arm 48 in its third position, conductors 43 and 44, front contact and armature of relay 15 to ground. The relay 23 is made marginal and therefore does not pull up its armature at .this time. If the called party is in at this time he removes his receiver in re sponse to the call. The resistance of the ringer is thereby shunted by the closure of the switch hook contacts and the relay 23 now receives enough current to attract its armature. The attraction of the relay 23 opens the circuit of magnet 22 which thereby deenergizes. The deenergization of magnet 22 cuts off the ringing current generator and also passes the side switch into fourth position. The arms 48 and 49 by mm'ing to their fourth contacts complete a talking circuit from the calling to the called substations and conversation may proceed. Battery current is fed to the calling telephone line through relay 15, and to the called line through relay 34.

At the end of conversation, if the calling subscriber is the first to replace his receiver. the circuit of relay 15 is broken and, said relay being quicker acting than the relay 18, retracts its armature while the armatures of relay 18 are maintained closed for an appreciable time. During this time a ground is placed upon the terminal 13 as follows to release the preceding switches: ground, armature and back contact of relay 15, arma ture and front contact of relay 18, sideswitch arm 21 in its fourth position, conductor 52. front contact and lefthand armature of relay 34. test wire 42 to terminal 13. \Vhen the called subscriber hangs up his receiver the line relay 34 retracts its armatures and a circuit is thereby completed for the release magnet of the connector, extending from battery, right-hand winding of RM. right-hand armature and contact of relay 31, off-normal contact 35, conductor 53, back contact and left-hand armature of relay 18. conductor 12. left-hand armature and back contact of relay 31. conductor 11. back contact and right-hand armature of relay 18, back contact and armature of relay 15 to ground. Magnet RM energizes in this circuit and restores the connector switch to normal.

Coming now to the condition wherein my present invention is of special utility. let it be assumed that the called party is out at the time, or is not within hearing distance of his telephone ringer. The connector is now in ringing position and ringing current will be supplied to the called line until the subscriber at station 1 replaces his receiver to abandon the call. However, in accordance with the present invention. after having waited a reasonable length of time without receiving response, the scriber may, if he so desires, operate his sending transmitter or equi 'alent means to send another series of impulses over the line. This latter set of impulses prints. perforates or otherwise produces a record on a paper tape or the like at the called substation, showing the desired party upon his return, that in his absence a call was made, and furthermore the number of the calling station. To this end each substation is provided with a bridging circuit across the line comprising an'electro-magnet 51 and a condenser This bridge is tuned so that the magnet 51 is responsive to a source of alternating current of a given frequency, whereas on the other hand, it does not respond to the ordinary frequency ringing current. The magnet 51 has an armature 56 carrying a pawl 57 and a recording finger At each actuation of armature 56 the finger '58 is pressed against a tape 59 running over a tape wheel 60, thereby producing a dot upon the tape for, each impulse sent. Engagement of the pawl 57 with ratchet (31 advances the tape to bring a fresh surface beneath the recording finger. Inasmuch as recording devices of this class are old and well known I have deemed it unnecessary to show or describe the same in detail herein.

l pon the calling subscriber operating his sender to send the recording impulses, the connector line relay 15 vibrates its armature in the same manner as when the selective impulses were being transmitted. At the first opening of the line. and when the relay 15'retracts its armature in response thereto.-a circuit is completed as follows: ground, armature and back contact of relay 15, armature and front contact of relay 18, side-switch arm 21 in its third position, Winding of slow releasing relay 62 to battery and ground. The relay 62 attracts its armature and prepares a circuit for a sec- -alling sub-' ond slow releasing relay -16. This circuit is completed when relay 15 again attracts its armature, and leads from ground. armature and front contact of relay 15, conductor 11, armature and contact of relay (32, relay 1G, to battery and ground. The relay 16, by energizing. opens the previously traced circuit of the ringing current at its armature and back contact, and at its frontcontact completes a circuit for the special frequency source 63. Such circuit is traceable from ground, special frequency machine 63, front contact and armature of relay 16, conductor 17, side-switch arm 19 in its third position, wiper 26, terminal 29. conductor 51. magnet 51, condenser 55, conductor 50, terminal 28, wiper 25, sideswitch arm 18, conductors 13 and 11, front contact and armature of relay 15 to ground. Thus at the closure of its armature and front contact at the first impulse, the relay 15 establishes a circuit for the slow releasing relay 16, which by attracting its arma ture, cuts out the ringing current and substitutes therefor a special source of current ('53. In response to this special source the magnet 5-1 energizes and produces a dot upon the tape 59. hen the next impulse is sent the relay 15 vibrates its armature to interrupt the circuit of the special frequency current and permits the second dot to be recorded on the tape, and so on. At the end of the first set of impulses the wheel 60. having acquired an appreciable amount of momentum, continues to rotate during the interval intervening the first and second sets ofimpulses. This has the effect of producing either a blank space or a continuous dash between the sets of dots on the tape, according as the relays 62 and 46 release their armatures to cut off the special source of current between sets of impulses or are made sufliciently slow to retain their armatures until the subscriber sends in the next set of impulses. In either case the result is the same. For each set of impulses sent by the subscriber at station 1 a corresponding set of dots will be. recorded upon the tape 59, with a space between sets, so that the observer can readily determine the designation recorded. After the calling subscriber has thus recorded a designation corresponding to his own number upon the tape 59 atthe called station he hangs up his receiver to restore the switches to their normal position.

In order to avoid operating the sender 7 the calling station may be provided with a special sender, as, for instance, a district messenger box, which is adapted by a single operation to send out impulses corresponding to the number of the station to which it is individual.

I also wish to have it understood that other such obvious modifications may be made without departing fromthe spirit of the invention.

What is claimed is:

1. In a telephone system, a calling and a called line, substations therefor, means including automatic switches for interconnecting said lines, a source of current for operating said'switches, recording means located at one of said substations, a sourceof special current for operating said recording means, and means associated with one of the automatic switches and variably controlled from the other of said substations for causing said special current to operate said recording means. I

Y 2. In a telephone system, subscribers lines and substations, a connector switch for establishing a connection between a calling line and a called line, a source of ringing current, a source of current of special character, said connector switch being adapted to connect said ringing current source to the called line, means associated with the connector switch and controlled at the calling substation for removing the source of ringing current from the called line and substituting therefor said special source, and recording means at the called station responsive to said special source of current.

3. In a telephone system, subscribers lines and substations, a connector switch having a stepping relay for controlling the same to connect a calling line to a called line, an impulse sending device at the calling substation for operating said relay, a source of ringing current adapted to be applied to the called line by said connector switch, a source of special frequency current, means whereby the operation of the stepping relay, when the connector switch is in its ringing position, causes said ringing current to be removed from the called line and the special frequency source to be substituted in its stead, and recording means at the called substation responsive to said special frequency current but not responsive to the ringing current.

4. In a telephone system, subscribers lines and substations, a connector switch, means for extending the calling line thereto, a stepping relay for the connector switch, an impulse sender at thev calling substation for operating said relay, means responsive to the operation of said relay for moving said switch into connection with a called line, a source of ringing current and means associated with the connector switch for applying the same to the called line, a source of special frequency current, means whereby when said stepping relay is operated with the connector in its ringing position, said ringing source is disconnected from the called line and the special source substituted in its place to send over said line series ofv impulses in accordance with the actuation of said relay, and recording means at the called substation responsive to said special frequency impulses.

5. In a telephone system, subscribers lines and substations, a connector switch with operating means therefor adapted to assume successive stages of operation for the purpose of establishing a connection between a calling and a called line, a source of ringing current, a source of current of special character, means for applying the source of ringing current to the called line when the connector is in a particular stage of its operation, means associated with said connector and controlled from the calling substation to substitute said source of current of special character for the ringing current, and recording means at the called substation responsive to said special current.

6. In a telephone system, an incoming line, an outgoing line, a substation in which the outgoing line terminates, a recording device associated with said substation, means including an automatic switch for interconnecting said lines, a source of current for operatingsaid switch, a source of special current for operating said recording device, and means variably controlled from a distant point for causing said special current to actuate said recording device.

7. In a telephone system, an incoming and an outgoing line, an automatic switch for interconnecting said lines, a source of current for operating said switch, a recording device associated with the outgoing line, a source of special current for operating said recording device, and an impulse sender associated with the incoming line for controlling the two sources of current and thereby controlling the operation of said automatic switch and said recording device.

8. In a telephone system, subscribers lines and substations, a connector switch with op;-

erating means therefor adapted to assume successive stages of operation for 'the purpose of establishing a connection between a calling and a called line, a source of operating current, a source of current of special character, means for applying the source of operating current to the called line when the connector is in a particular stage of its opoperating current to the called line when the automatic switch is in a particular stage of its operation, means associated with said automatic switch and controlled from the calling substation to substitute said source of current of special character for the operating current, and recording means at the 'called substation responsive to said special current.

10. In a telephone system, a calling and a called line, substations therefor, means ineluding automatic switches for interconnecting said lines, two signal means located at the called substation, and means associated with one of the automatic switches and controlled from the other of said substations for operating at will either of said signal means.

In witness whereof, I hereunto subscribe my name this 21st day of July A. 1)., 1917 20 CHARLES GOODRUM. 

